Apparatus for treating metals



Sept. 10, 1940. E. H. GREENBERG APPARATUS FOR TREATING METALS 3Sheets-Sheet 1 Filed Dec.

. INVENTOR 5/020 1 're nbf? BY 1 I haul MK /V ATTORNEY Sept. 10, 1940.

E. H. GREENBERG APPARATUS FOR TREATING METALS Filed Dec. 16, 1956 3Sheets-Sheet 2 INVENTOR 70121 H Greenhy ATTOR EY Sept. 10, 1940.-

E. H. GREENBERG APPARATUS FOR TREATING METALS a Sheets-Sheet 3 FiledDec. 16, 1936 /M a i a W 5 Patented Sept. '10, 194a UNITED STATES.

PATENT OFFICE 9 Claims.

This invention relates to 'an apparatus and process for treating metalsand particularly for detinning lead alloys. It is especially concernedwith such apparatus and process for the production and removal of tin asvolatfle tin tetrachloride from alloys or mixtures containing lead andtin.

It is known that chlorine gas will react with lead and tin to form leadchloride and stannous chloride. 'Stannous chloride in the presence ofmore chlorine is changed into stannic chloride which is volatile at aknown elevated temperature and by heating to that temperature shouldtheoretically be removable from the lead chloride which is not volatilewhen heated to that. temperature. Apparatuses and processes have beenheretofore proposed utilizing this principle for separation of tin, butvarious diiliculties have been encountered due in part to lack ofappreciation of the proper conditions for operation and 1 in part to thehighly corrosive and poisonous nature of chlorine gas, particularly athigh-temperatures. The use of chlorine on mixtures of alloys containinglead and tin at low temperatures where the metal is in granular but notmelted state, is not practical because the chlorine attacks the exteriorof the granules but the chlorides formed then prevent contact of thechlorine with the metals underneath. Operation at higher temperatureshas not been practical prior to the present invention, so far as I amaware, because of difflculties in providing a suitable apparatusandprocess that could be operated ecor nomically and efliciently to producethe desired results.

. The principal object of my invention accordingly is to overcome atleast some of the dimculties heretofore recognized and to provide apractical apparatus and process for the desired removal of tin frommixtures or alloys containing lead and tin with or without other metals.

The invention accordingly comprises the novel apparatus and combinationsthereof, as well as a the novel processes and steps of processes whichmay be carried out in such apparatus, specific Fig. 1 is a diagrammaticelevation partly in section of the apparatus;

(class-s4) Fig. 2 is an enlarged detail section of the reaction chamber;Fig. 3 is a cross-section thereof on the line 3-3 of Fig.2; e

Fig. 4 isan enlarged detail view of one ofthe plurality of chlorinepipes passing from a bustle pipe into the reaction chamber;

Fig. 5 is a diagrammatic view partly in section of a modification of thekettle and reaction chambers in which two kettles are employed provided.

so that a constant level of molten metal may be maintained easily in thekettle in which the reaction chamber is placed;

Fig. 6 is a diagrammatic elevation partly in section ofanother'modification of the apparatus showing three kettles permittingcontinuous operation of the process; and

Fig. 7 is a' diagrammatic elevation partly in section showing amodification of the apparatus shown in Fig. 5 and in place of the secondkettle employing a furnace with a bay in which the pump works.

Because of the corrosive and poisonous character of chlorine, especiallyat temperatures of 1000-1050 F. at which I prefer to practice theprocess of the invention as described below, I have shown in thedrawings an apparatus in which the chlorine, while combining with thetin, operates in a comparatively restricted area. In that area theapparatus is preferably lined with a chlorine-resistant material whichis described and claimed in my copending application Ser. No. 120,877,filed January 16, 1937. In addition the chlorine is confined within thisarea so that its escape beyondit in any substantial quantity isprevented. If small quantities pass off with the volatilized tinchloride they are collected by washing, as later described. J

Referring now to the drawings and particularly to Figs. 1 to 4, thenumeral I designates an open steel kettle supported in a; kettle setting2. 3 is a burner which may be operated by oil or gas and passes througha port in the kettle setting in order to heat the kettle I. 4 is aframework of channel iron or similar structure extending across the topof the kettle to support, the reaction chamber and other apparatushereinafter described. -5 is an electric motor mounted on the channeliron 4 and serving to operate the pump 6. This pump per se is describedand claimed in my copending application Ser. No. 118,704, filed January2, 1937. The pump is connected by pipe I with 'a cylindrical reactionchamber open at the bottom, which has an outer shell of cast iron 8lined on the inside with feed pipes It.

clay brick 9 (see Figs. 2 and 3). Inside the clay brick 9 is a specialconcrete layer it adapted to withstand the corrosive effects of chlorineat the temperatures above mentioned. This concrete by the framework tand when in operative position its lower edge will be immersedin themetal inside the'kettle to a depth of about 16 inches approximately.

H is a tank containing chlorine which is led by a pipe E2 to amanifoldor bustle pipe it which distributes the chlorine to a number of smallThese chlorine-pipes are composed of special nickel, molybdenum,chromium,

@ iron alloy tubes,.preferably the alloy known as Hastelloy which isresistant to chlorine and lead and tin chlorides at temperatures of theorder of 1000 F. The tubes are approximately inside diameter when thedimensions given aelajcn chamber. They are such as to provide a properworking depth of lead chloride and stannous chloride but to minimize thequantity of chlorides required for the operation by confining suchrepresents control valves and a flow meter for regulating the amount ofchlorine passing to the bustle pipe l3 and thence into the chlorinepipes M. ,This assembly serves to deliver'chlorlne gas in a number offine streams under con-,

trolled conditions. 7,

it represents a pipe for conducting tin tetrachloride formed in thereaction chamber away therefrom and into a pre-cooler .19, which isadapted to cool the gases and precipitate-any.

entrained stannous and lead chloride prior to the gases reaching thewater-cooled condenser 20 in which the tin tetrachloride is condensed toa liquid which is collected in the. container 2| is that referred to inmy copending application chlorides in a small space. This is animportant 5 Ser. No. 120,877 above, and is composed of considerationbecause at the end of the opera crushed fire brick, Portland cement withhigh tion the amount of chlorides formed-in order to alumina content andsand. This cement as carryout the detinning operation is kept at a shownprotects the various parts of the appaminimum and consequently theamount of pure l0 ratus which it surrounds from the corrosive acmetalsrecovered is correspondingly'larger. I i0 tion of the chlorine gas andmolten chloride. have found that it is important to maintain a The pipeLit will be noted passes through the sufilcient depth of metal chloridesin the reactop of this reaction chamber and terminates a tion chamber sothat with spressure of 3 to 5 little below the top ofthe reactionchamber lbs, or perhaps a little more, of chlorine gas passing throughthe cement iii and discharging as I prefer to use, there is a sumcientdepth of 145 into a substantially cylindrical space about the chloridesto react emciently with the chlorine center of the reaction chamber,into which space andmetallic lead and tin entering the chamber stannicchloride rises on its way out of the reso as'to avoid use of anexcessive quantity of salt action chamber. Through the pipe I isadaptlayer. The dimensions of the chamber are also ed to be deliveredmolten metal including lead such that the amount of surface exposed tothe andtin from the pump 6, the metal including corrosive action of thechlorine and molten chlolead and tin being constantly circulated throughrides is about assmall as could be satisfactorily this chamber. Whilethe pipe is shown as delivemployed for practical working conditions.ering the stream 01' metal including lead and tin Each of the chlorinefeed pipes is connected 25 straight downward, it may be inclined at anwith-the'bustle pipe by a T connection in which 25 angle so that thestream of metal will promote a is provided a cock 16 in order toregulate the instirring action of the contents in the chamber dividualflowthrough its feed pipe. The upper or the stream may be made to hit abaiile plate end'of each chlorine pipe is provided with a plug tosubdivide it. lea, which may be removed in order to clean out Thereaction chamber as shown is supported the pipe ii and when necessary.The numeral I1 45 herein for other parts of the apparatus areemsupported t erebelow- 22 s a p pe on uct 4i loyed. These tubes areprotected by graphite the non-condcnsa c p r n f s p in from tubes mewhich are slipped over them, the it, and w ich su y consists g c n e. oa' graphite extending the entire length of the tubes W i we Which y befil d wi h it inside the reaction chamber. The graphite tubes pa nmaterial through which di e caustic 5 are held in place about the steeltubes by a cesoda solution is circulated by the system comi: ment Mbconsisting of silica sand, finely groundv p d a p tank 25 Where thecaustic a, brick and high alumina cement or sodium siliafter Passingthrough e w collects and cate. These chlorine pipes extend from the busow c is P p y the m pr pe ated tle pipe through the cover of the reactioncham- P p 35 end returned to the D of e Washv her and being ofsufilcient length so'that when 8' t we y the P p The pparatus in- 55 thereaction chamber is positioned about 16' cluding the pipe 22 and washingtower 23 is not inches below the surface of the metal, as indin ss e POf the equipment It is p ocated above, the lower ends% of these chlorineVlded catch y Volatile p u spass nc bepipes are about 3 to 5 inchesbelow the surface y d th condenser it due to p r peraw of the metal bathinside the reaction chamber. t on of the Promise They surround thecentral space in the reaction 27 s e' p e e co nected to the chamber.The bottom edge i5 of the reaction p of e Washing tower 23 w ich servesto chamber is about 13 inches below the outlets of e p the entire a y emfrolil reaction chamthe chlorine ipes 14. With these dimensions r to a dincluding t sh under a sli ht the diameter of the reaction chamber isapprox-' l t8 imately 29 inches and its height approximately he p nofthe pp t s Sh wn in Figs. 0 31 inches and the length of the chlorinetubes 1 to 4 is briefly as fcllcws- The metal alloy or f m the cover totheir point of discharge in the othe metal mass containing d nd tin.with reaction chamber is about 18' inches; The dior without otheringredients, is melted inthe.

mensions are given because for the embodiment kettle I and heated to thete pe a ure e p y d 70 in operating the process as later described. Thepump 6 is started to circulate the molten lead tin through the reactionchamber. Simultaneouslychlorine gas at a measured rate is allowed toflow into the molten metal from the chlorine shown I have obtainedexcellent results by having the parts proportioned as indicated,although the invention of1course is not restricted to such dimensions.These dimensions have :5 been worked out to give a practical reactiontank ll through the bustle pipe l3 and chlorine feed pipes. Tintetrachloride is formed in the reaction chamber and volatilized. Thevapor leaves the reaction chamber by means of the pipe f 18, passesthrough the pre-cooler l9 where occasionally small amounts of stannousand lead chlo- The cooled tin tetrachloride.

which is provided as a precautionary measure,-

passing in at the bottom of the tower 23 where the gases are washed withcirculating dilute caustic soda.

In Fig. 5 there is shown a modified form of apparatus comprising twokettlesettings. Kettle 28 is preferably much larger than kettle 29. Thisapparatus is devised in order that a constant level may be maintained inkettle 29 during the operation. It will be understoodof course that inoperating, for example as in Fig. 1, the mass of molten material in thekettle l gradually becomes lower due to the removal of tin astetrachloride therefrom. Such lowering of the molten metal may becompensated for by feeding fresh metal into the pot during the earlyperiod of treatment, but this should be discontinued if the greater partof the tin is to' be separated as tin tetrachloride, if the operation isto be conducted economically. In addition it would be diificult, if notimpossible, to raise and lower the reaction chamber, because of thevarious feed and delivery pipes connected to it, in order to keep itproperly immersed in the shrinking bath if no new metal is addedthereto. It is important that the relation of the tips of the chlorinefeed pipes with the metal and chloride bath be maintained substantiallyas indicated above and if there is any substantial deviation the smoothprogress of the reaction may be interrupted.

Accordingly I have provided in Fig. 5 an apparatus in which a constantlevel is maintained in the kettle 29. In this latter kettle the reactionchamber withits outer wall 8, chlorine pipes 14, bustle pipe 13 andother associated parts are the same as desribed in Fig. 1, andaresupported by a casting 30 on thetop of the kettle 29. This casting ispreferably solid and provides a cover for the kettle 29. The kettle 28,however, contains the pump B-and pipe 1 leading therefrom into thereaction chamber. The pum'p 6 is supported by a casting 31 supported onthe edges of the kettle. A pipe 31a serves to circulate the molten metalbetween the kettles 28' and 29. When the metal rises above the desiredheight in kettle, 29, it flows over into kettle 28. Bumers 32 and 33 maybe introduced through the brick walls of the kettle supports 2 andeither or both' kettles 23 and 29 maybe heated, if desired.

The modification shown in Fig. 7 is similar to that shown in Fig. 5, butkettle 28 in this instance is replaced by a furnace 34, which has anoutside bay 35 communicating-with the interior, which bay contains alimited quantity of molten metal and in which baythe pump 6 is placeddelivering molten metal by pipe- I to the reaction chamber. The kettle.29 is supported on a kettle base which in turn is elevated on a steelstructure 39. The kettle is supported at'sufli cient height so that itis above the furnace 34' and so that an overflow pipe 31 will removemolten metal from the kettle 29 and depositit in the furnace 34 when themetal in kettle 2 9 rises above the desired level.

The operationof the apparatus shown in Figs. f

5 and? is similar to that shown in Fig. 1.

'A still further modification is shown in Fig. 6 to provide asubstantially continuous process. In this instance three kettles 38, 39and 40 are provided. The center kettle 38 corresponds to the kettle I inFig. 1 and this kettle operates alternately with either kettle 39 orkettle 40. Some time may be lost in heating up a bath of metal to1000-1050 F. which is the preferred temperature for detinning accordingto the process described below. Considerable time is also 'lost incooling the metal bath after detinning so. that it may be cast. By thearrangement shown in Fig. 6 practically continuous operation may bemaintained. While metal in kettle 40 is being detinned, the metal in39'is being cooled, cast and a new lot introduced, melted and brought upto the temperature above mentioned. The reaction chamber is situatedinkettle 38 and with its associated parts is substantially the same asthat shown in Fig. 5, being supported by a solid casting which serves asa cover for the kett1e 38. Only a single pump 6 may be employed and whenit has finished its operation in one kettie, 49 for example, it may bedetached and transferred to the other kettle 39 for operation. Overflowpipes 41 and 42, provided respectively with stoppers 43 and 44, extendfrom the kettle 39 and deliver into the adjacent kettles, pipe Mdelivering into kettle 49 an'd'pipe 42 delivering into kettle 39. Theoperation of this embodiment is as follows. Metalis charged for instanceinto .kettle 39, heated to .a process temperature,

pumped through pipe I and delivered into the reaction chamber. Chlorineis delivered from its source through the bustle pipe 13 and chlorinepipes 14 into the reaction chamber and stannic chloride passes oilthrough pipe l8 through the condensing system shown in Fig. 1. Duringthe processthe pump 6 is delivering the molten metal as stated throughthe pipe I to the' reaction chamber and the overflow pipe 41 being openby removal of its stopper 43, metal over--v flows from the kettle 38into the kettle 40 and .then is again returned by the pump. Prior to thecompletion of the detinning of the metal in 49., another charge of metalis placed in kettle 39 and heated up to process temperature. Whendetinning is completed in 40 the pump 6 with its piping l is' shifted tokettle 39 and theprocess of detinning similar to that describedinconnection with kettle 40 is carried on here, but at this time theoverflow pipe 4| is closed. by stopper-43 so that the overflow occursfrom pipe 42, its stop- Eli per 44 having been removed. While thedetinning isv occurring in kettle 39,'the detinned materialin 49 iscooling and being cast. After the .detinning in kettle-'39, the processthen proceeds in' 40 once more. In other words the kettles 39 and 40 arealternately used for the heating and detinning operation and then forthe cooling opvention that when chlorine is injected into'fia moltenlead-tin mixtureor alloy'with or-without= antimony, lead chloride andstannous chloride are formed and these salts will float to the surface.The reaction involved is:

If further chlorine comes in contact with these salts-lead chloride andstannous chloride, there wil be formed stannic chloride which isvolatile at about 238 F., and the temperature of the lead chloride andstannous chloride being above thispoint, the stannic chloride will bevolatilized and is removed from the mass. As the stannic chloride isremoved, further quantities of stannous chloride must be formed, whichin turn reacts with a further quantity of chlorine to produce stannicchloride.

I have found in accordance with my invention that-it is important tokeep the five chief reacting materials involved in the production of tintetrachloride from mixtures containing lead and tin, namely tin, lead,stannous chloride, lead chloride and chlorine, all in active contactwith one another. It is important to have a large surface of chlorineexposed to the reacting materials. It. is also important to keep themetal salts in constant agitation so that the other three reactingmaterials may come in contact with them. If ordinary mechanicalagitators are employed, it is diflicult -to keep any agitation equipmentin operation because of' the terrific attack -by the chloride at theelevated temperature,

which I prefer to bein excess of 1000""F.

I have found that by introducing chlorine into a'reaction chamber incontact with molten metal containing tin and, lead and perhaps otheringredients, forming a' salt layer containing lead and stannous chlorideand discharging a stream of molten metal containing lead/tin and pen,haps other ingredients through this salt layer,

that I can satisfactorily produce tin tetrachloride. Under properconditions which will be given in "greater detail below, the process canbe conducted economically and efliciently. AlthoughI do not wish to bebound by the following explanation, there appears to occur under theseconditions the establishment of an equilibrium or balance between the.components lead chloride, stannous chloride, lead and tin, which balanceis being continuously upset by the introduction of further .quantitiesofchlorine. Chlorine reacts with the stannous chloride to form tintetrachloride which is then volatilized. The equilibrium being upset isthen restored by the formation of stannous chloride by reaction of tinwith lead chloride.

The reactions mentioned are as follows:

' sn+c1=- snc12 SnCla+Cl2 SnCl4 (tin tetrachloride volatilizes)PbCla-i-Sn Pb+SnClz (stannous choride) The amnity of the differentmetals and their lower chlorides or chlorine are such that very littleantimony or arsenic, if any be present,

goes into the salt layer and the resulting tin dinarily below thetemperature'of the chlorinating zone. Even though the temperature of thesalt layer in the reaction chamber tends to be higher than the moltenbath of lead, tin and other metals with which it is in contact,nevertheless the temperature of this molten bath because of the largevolume of metal therein is lower than that imthe reaction chamber andfurthermore a certain amount of cooling of this molten metal occursduring the pumping operation so that the molten metal delivered by thepump into the reaction chamber is at a temperature where it aids inmaintaining the tem-' perature of the reaction chamber within thedesired limits. Accordingly after the chlorinating reaction has startedin thereaction chamber, it is ordinarily not necessary to apply heat tothe kettle to raise or maintain the temperature of the metal, but ifthis should be necessary of course the kettle may be heated bythe burnershown thereunder in the above embodiments of the apparatus.

The following is a description of an embodiment of the process as I nowprefer to practice it: A charge of material containing lead and tinusually. in the form of a lead alloy of about important to keep thetemperature somewhat above this melting point in order to avoidpluggingthe pipes ll through which the chlorine 8 's emerges. The molten alloyis circulated from the kettle I through the pump 6 and through thereaction chamber and chlorine is fed into the reaction chamber from thetank II. The chlorine reacts with the metal to build up a salt layer of.lead chloride and stannous chloride and the molten alloy passing intothe reaction chamber.is discharged through this salt layer by the pump 6at a rate of 25,000 to 40,000 lbs. per hour. The reaction chamber asnoted in the description of the apparatus is suitably positioned belowthe surface of the molten metal. Where the diameter of the reactionchamber is about 29 inches and its height approximately 31" inches, thereaction chamber will be about 16 inches belowthe surface of the metaland the ends of the chlorine tubes from the cover of the reactionchamber to their point of discharge will be about 18 inches and theywill terminate, therefore, about 13 inches from the bottom of thereaction chamber. The chlorine is delivered to the reaction chamberunder a pressure of about 3 to 5 lbs. per square inch and the rate ofdelivery of the chlorine is controlled by the control valves and Percenttin in metal 1 5 3 2 13 1 s u 200 o.75. 100 0.50 50 During the firstthree or four hours of feeding chlorine gas, substantially no tintetrachloride is Lead chloride has a melting layer formed is such thatwith chlorine gas at 3 to 5 lbs. per sq. inchthe chlorine will penetrateto and react as far as the bottom of the layer but will not emergesubstantially beyond it. From this time on it appears that the chlorinegas entering the salt layer reacts with the stannous chloride to form avolatile tetrachloride and upon depletion of the stannous chloride in'this way the reactions above mentioned to reestablish the equilibriumappear to occur. When the metal left in the kettle I contains above0.25% tin, the.

operation is considered finished as this is about the lowest content oftin that can be ordinarily obtained commercially. I

The tin tetrachloride produced is preferably conducted to a pre-coolerI9 where any entrained liquids or-high boiling liquids, which can becondensed at a higher temperature than that required for tintetrachloride, are removed from the tin tetrachloride and returned tothe'reaction, chamber by gravity. The tin tetrachloride vapor thenpasses to the condenser 20 where it is condensed to a liquid and isaccumulated in the container 2| for subsequent use. Any tintetrachloride not condensed in 20 or any chlorine gas notconsumed in thereaction chamber and passed along with the tin tetrachloride is washedout with caustic soda solution. -Very little chlorine gas in practiceneeds to be washed out as the efliciency of chlorine absorption in thereaction chamber is high.

At the end of a run which ordinarily lasts two to three days dependingon the original tin content of the metal being treated, there-remains inthe reaction chamber and floating on the metal bath about 2% of leadchloride of the original weight of alloy treated.

As the tin is eliminated as tin tetrachloride, the level of themetal-bath in the kettle I is progressively lowered. As it is importantto keep the metal level approximatelyconstant for efficient operation, Ifeed in fresh quantities of metal to the kettle I during the run inorder to maintain the original level. It is advantageous to use for thispurpose metal richer in tin than the original metal so that theproduction of tin tetrachloride is maintained at the maximum.

I have treated compositions containing not only lead and, tin but alsocontaining from 2.5 to 19%.

antimony and have found that the antimony contents had no adverseeffects 'on the removal of the tin. In treating one composition whichcontained Per cent Tin 1.7 to 21 Bismuth 0 to' 7 Copper f trace to 5Arsenic 0.1 to 4 Antimony 8 to 26 and the balance lead.

In accordance with my experience in practicing my invention, I havefound that the best resultsare obtained when lead tin alloys are usedwhich contain substantially no other ingredients or only smallproportions of other ingredients which are present as the raw materialsubjected to the process. I do not add catalysts such as sulfides,antimony or other ingredients to the raw material being treated, and Iprefer to remove sulphur if it is present in the metal being treated.

The tetrachloride of tin produced .by the process is remarkably purewhen considering the impurity .of the various compositions treated. Ihave found it to contain not over .04 to .9 2% of such impurities with99.96% to 99.08% of tin tetrachloride. The impurities found in the tintetrachloride will depend upon the'quality of the metal being treated.The. apparatus described above has been used satisfactorily in thecarrying out of the various process operations described.

A process which comprises among other things the maintenance of asubstantially constant level in the kettle where the reaction chamberislocated may'be carried out for example employing an apparatus likethat shown in Fig. 5. The lead and tin are melted in the kettles 28 and29 and the pump 6 started in kettle 28, chlorine being fed to thereaction chamber through the tubes It. A

chloride layer forms in the reaction chamber floating on the moltenmetal beneath. Chlorine comes in contact with the chloride layer and themetal being circulated by the pump. The stream of metal passing throughthe chloride layer passes into the kettle 29 and then overflows throughthe pipe 2 la into the kettle 28. Stannic chloride is removed throughthe pipe l8 and'may be condensed as heretofore described.

A similar process may be carried out employing the apparatus shown inFig. 7.

In carrying out a continuous process for separating tin as tetrachloridefrom alloys of mixtures containing tin and lead, I may employ anapparatus such as that shown in Fig. 6. Here lead is melted in thekettle 40 and pumped for example Iromyessel 40 through the reactionchamber'in vessel 38 where it comes in contact with a plural-. ity ofstreams of chlorine to form a separate layer of stannous chloride andlead chloride.

The

stream of molten lead pwses through the layer of vlead is heated in. thevessel 39 and circulated through the reaction chamber in contact withthe streams of chlorine to form a molten chloride layer and to producetin chloride. During this operation the metal in 40 is cooling so thatit may be cast. It is removed when cool and then prior to the detinningof the material in the kettle 39 a fresh lot of tin and lead isv placedin kettle 40 and heated up so thatjfwhen the detinning operation ceasesin kettle 39, another operation may .be started on the new metalinkettle 40 so that the process is operated continuously.

While the invention has been described in detail with respect toparticularpreferred examples,'it will be understood by those skilled inthe What is claimed as new and desired to be secured by Letters Patentof the United States is: 1. In apparatus for treating metals incombination, a container for molten metal, a reaction chamber within itand near the top thereof and opening into said container, means tocirculate said metal from said container through 'said reaction chamberand back to said container, means to maintain a layer of chlorides ontop of the molten metal in said container and within saidreactionchamber, and means-for passing chlorine in streams into saidlayer of chlorides.

2, In apparatus for treating metals in combination, a container fomolten metal, a reaction chamber within itZand near the top thereof andopening into sai container, 9. pump suspended in the container tocirculate said metal from said container through said reaction chamberand back to said container, means to form streams of chlorine in saidreaction chamber to react with said metal to form a layer of chlorideswhereby when the molten metal is in the container the chlorinated metalfioats thereon in the reaction chamber, the molten metal is circulatedthrough the 1 chlorides and the chlorine passes into the chlorides inthe reaction chamber.

3. In apparatus for treating metals in combination, a container formolten metal, a reaction chamber within it and near the top thereof andopening into said container, means located from to said reactionchambenand a series of pipes in said reaction chamber to conduct thechlorine therethrough in streams and to react with said metal to form alayer of chlorides whereby when the molten metalis in the container thechlorinated metal floats thereon in the reaction chamber, the moltenmetal is circulated through the chlorides and the chlorine passes intothe chlorinated metal in the reaction chamber.

4. In apparatus for treating metals in combination, a kettle for moltenmetal including lead and tin, a reaction chamber within it open at thebottom and adapted to dip into the metal and allow the metal to risetherein when the latter fills the kettle to a point near the 'top, saidchamber being lined with material refractory to lead and tin chloridesat a temperature about 1000-1050 F., a pump in saidkettle to circulatesaid metal from the kettle through said reaction chamber and back tosaid kettle, a source of chlorine delivering chlorine to said reactionchamber and a series of metal alloy tubes surrounded by graphite andpassing through the refractory material to a position a short distanceabove the lower edge of the reaction chamber, said tubes being adaptedto conduct chlorine in a series of streams into an open space in thereaction chamber adapted to be partially occupied by said molten metal,whereby upon chlorine cominginto contact with the molten metal in thereaction chamber a layer of chlorinated metal is formed floating on themolten metalbeneath and when the molten metal is pumped from the kettleto the reactioii chamber it passes through the chlorinated metal layerat the same time that the chlorine "passes, ir'itocontact with thestream of molten metal delivered by the and the chlorinated means forcirculating metal from below saidlayer and discharging it above and intosaid layer, means to conduct away the volatile chloride of tin, and acondenser to condense and recover said volatilized tin.

6. In apparatus for treating metals in combination, a container formolten metalincluding tin, a reaction chamber near the top thereof andopening into said container, a second container for molten metal, meansto circulate said metal successively through the containers and thereaction chamber, means to bring streams of chlorine in said reactionchamber into reaction with said metal to form a layer of chlorides, andto form and remove stannic chloride from the reaction chamber wherebythe level of the molten metal in said first mentioned container may bemaintained substantially constant'regardless of the removal of tin astin tetrachloride from the molten metal.

7. In a continuous apparatus for separating tin from alloys or mixturescontaining tin and lead in combination, a reaction kettle having areaction chamber. located therein, a second kettle communicatingtherewith, and a third kettle communicating with said reaction kettle,said second and third kettles being adapted to be I alternatively put incommunication with said reaction kettle, apump adapted to be locatedalternatively in the second or third kettle for circulating molten metalfrom for example the secgnd kettle in which it is located through thethe reaction chamber continuously, whereby two lots of metal may besuccessively acted upon in thereaction chamber and after one lot hasbeen treated itmat be allowed to cool for casting while the second lotis being passed through the reaction chamber.

8. In an apparatus for treating metals in com- I bination, means tomaintains. layer of tin and lead chlorides on top of a molten metal bathcontaining tin and 1e d, means for passing chlorine into said layer 0chlorides, and means for circulating metal from below said layer anddis-'- charging it on or into said layer.

9. A reaction chamber for the separation o metallic constituents ofmetals or alloys of the ture of leadand tin by a treatment of vapor ofhalogen consisting of a hollow metallic body suspended in the moltenmetal or alloy in such a manner that an eiiicient seal is obtained,distributing ducts penetratingsaid hollow ,metallio J body and ending inopenings in a substantially non-metallic" refractory lining adjoiningsaid "hollow metallic body, an opening above the level of the moltenmetal or alloy for the admisexit of reaction products.

'sion of saline into said reaction chamber and an

